Mark empty default constructors as =default if it makes the type POD

NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234694 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/EpochTracker.h

@@ -30,7 +30,7 @@ public:
 
   class HandleBase {
   public:
-    HandleBase() {}
+    HandleBase() = default;
     explicit HandleBase(const DebugEpochBase *) {}
     bool isHandleInSync() const { return true; }
     const void *getEpochAddress() const { return nullptr; }

include/llvm/ADT/Hashing.h

@@ -75,7 +75,7 @@ class hash_code {
 public:
   /// \brief Default construct a hash_code.
   /// Note that this leaves the value uninitialized.
-  hash_code() {}
+  hash_code() = default;
 
   /// \brief Form a hash code directly from a numerical value.
   hash_code(size_t value) : value(value) {}

include/llvm/ADT/iterator.h

@@ -150,7 +150,7 @@ class iterator_adaptor_base
 protected:
   WrappedIteratorT I;
 
-  iterator_adaptor_base() {}
+  iterator_adaptor_base() = default;
 
   template <typename U>
   explicit iterator_adaptor_base(
@@ -231,7 +231,7 @@ struct pointee_iterator
           pointee_iterator<WrappedIteratorT>, WrappedIteratorT,
           typename std::iterator_traits<WrappedIteratorT>::iterator_category,
           T> {
-  pointee_iterator() {}
+  pointee_iterator() = default;
   template <typename U>
   pointee_iterator(U &&u)
       : pointee_iterator::iterator_adaptor_base(std::forward<U &&>(u)) {}

include/llvm/Support/FileSystem.h

@@ -120,7 +120,7 @@ class UniqueID {
   uint64_t File;
 
 public:
-  UniqueID() {}
+  UniqueID() = default;
   UniqueID(uint64_t Device, uint64_t File) : Device(Device), File(File) {}
   bool operator==(const UniqueID &Other) const {
     return Device == Other.Device && File == Other.File;

lib/Transforms/Instrumentation/GCOVProfiling.cpp

@@ -163,7 +163,7 @@ namespace {
     static const char *const BlockTag;
     static const char *const EdgeTag;
 
-    GCOVRecord() {}
+    GCOVRecord() = default;
 
     void writeBytes(const char *Bytes, int Size) {
       os->write(Bytes, Size);

lib/Transforms/Scalar/LoadCombine.cpp

@@ -41,9 +41,9 @@ struct PointerOffsetPair {
 };
 
 struct LoadPOPPair {
+  LoadPOPPair() = default;
   LoadPOPPair(LoadInst *L, PointerOffsetPair P, unsigned O)
       : Load(L), POP(P), InsertOrder(O) {}
-  LoadPOPPair() {}
   LoadInst *Load;
   PointerOffsetPair POP;
   /// \brief The new load needs to be created before the first load in IR order.

lib/Transforms/Scalar/LoopStrengthReduce.cpp

@@ -112,8 +112,6 @@ public:
   /// a particular register.
   SmallBitVector UsedByIndices;
 
-  RegSortData() {}
-
   void print(raw_ostream &OS) const;
   void dump() const;
 };

tools/yaml2obj/yaml2coff.cpp

@@ -253,10 +253,7 @@ binary_le_impl<value_type> binary_le(value_type V) {
   return binary_le_impl<value_type>(V);
 }
 
-template <size_t NumBytes>
-struct zeros_impl {
-  zeros_impl() {}
-};
+template <size_t NumBytes> struct zeros_impl {};
 
 template <size_t NumBytes>
 raw_ostream &operator<<(raw_ostream &OS, const zeros_impl<NumBytes> &) {